Having a horizontal surface without a slope, tilt, or curvature.
Having a smooth, even, level surface: a skirt sewed with fine flat seams.
Having a relatively broad surface in relation to thickness or depth: a flat board. See Synonyms at level.
Stretched out or lying at full length along the ground; prone.
Free of qualification; absolute: a flat refusal.
Fixed; unvarying: a flat rate.
Lacking interest or excitement; dull: a flat scenario.
Lacking in flavor: a flat stew that needs salt.
Having lost effervescence or sparkle: flat beer.
Deflated. Used of a tire.
Electrically discharged. Used of a storage battery.
Of or relating to a horizontal line that displays no ups or downs and signifies the absence of physiological activity: A flat electroencephalogram indicates a loss of brain function.
Commercially inactive; sluggish: flat sales for the month.
Unmodulated; monotonous: a flat voice.
Lacking variety in tint or shading; uniform: "The sky was bright but flat, the color of oyster shells” ( Anne Tyler).
Not glossy; mat: flat paint.
Music Being below the correct pitch.
Music Being one half step lower than the corresponding natural key: the key of B flat.
Designating the vowel a as pronounced in bad or cat.
Nautical Taut. Used of a sail.
Level with the ground; horizontally.
On or up against a flat surface; at full length.
So as to be flat.
Directly; completely: went flat against the rules; flat broke.